Martin Luther University of Halle-Wittenberg

About: Martin Luther University of Halle-Wittenberg is a education organization based out in Halle, Germany. It is known for research contribution in the topics: Population & Liquid crystal. The organization has 20232 authors who have published 38773 publications receiving 965004 citations. The organization is also known as: MLU & University of Wittenberg.

Qualitative and quantitative analysis of water‐soluble root exudates in relation to plant species and development

Abstract: The composition of root-derived substances is of great importance for the understanding of processes in the rhizosphere. Therefore, methods allowing a comprehensive collection and chemical analysis of the organic root exudates are necessary. In this study, we compare different methods with regard to their suitability to collect and characterize root exudates. Because the percolation or water logging method failed to quantitatively extract root exudates, a dipping method was developed which allowed an almost complete sampling of coldwater-soluble root exudates. By 14CO2 labeling of the shoots the composition of root exudates was found to be influenced by plant species and growth stage. In comparison to pea plants maize plants had a higher share of carboxylic acids and a lower share of sugars. Younger maize plants exuded considerably higher amounts of 14C labeled organic substances per g root dry matter than older ones. During plant development the relative amount of sugars decreased at the expense of carboxylic acids. The described methods are well suited for the elucidation of the influence of growth factors on root exudation. Qualitative und quantitative Analyse von Wurzelabscheidungen und ihre Abhangigkeit von Wachstumsfaktoren Die Zusammensetzung der Wurzelabscheidungen spielt fur das Verstandnis der Prozesse in der Rhizosphare eine immer grosere Rolle. Deshalb wurden verschiedene Methoden auf ihre Eignung gepruft. Durch eine Perkolation bzw. durch einen Uberstau des Anzuchtsubstrates war eine quantitative Extraktion der Wurzelabscheidungen nicht moglich. Daher wurde eine Eintauchmethode entwickelt, die die weitgehend vollstandige Erfassung der kaltwasserloslichen Wurzelabscheidungen erlaubt. Um die Abhangigkeit der Wurzelausscheidungen vom Pflanzenalter prufen zu konnen, wurden die Pflanzenprosse im interessierenden Entwicklungsstadium mit 14CO2 begast. Die Zusammensetzung der Wurzelabscheidungen hangt sowohl von der Pflanzenart als auch vom Pflanzenalter ab. Im Vergleich zu Erbsenpflanzen zeichneten sich die kaltwasserloslichen Wurzelabscheidungen bei Maispflanzen durch einen hoheren Carbonsaure- und niedrigeren Zuckeranteil aus. Jungere Maispflanzen gaben wesentlich hohere Mengen an 14C-markierten Wurzelabscheidungen je g Wurzeltrockenmasse ab als altere Pflanzen. Im Laufe der pflanzlichen Ontogenese nahm der Zuckeranteil zugunsten des Carbonsaureanteils relativ ab. Die vorgestellte Methode ist gut geeignet, den Einfluss von Wachstumsfaktoren auf die Abgabe organischer Substanzen uber die Wurzel zu erfassen.

Glutathione and Transition-Metal Homeostasis in Escherichia coli

Abstract: Glutathione (GSH) and its derivative phytochelatin are important binding factors in transition-metal homeostasis in many eukaryotes. Here, we demonstrate that GSH is also involved in chromate, Zn(II), Cd(II), and Cu(II) homeostasis and resistance in Escherichia coli. While the loss of the ability to synthesize GSH influenced metal tolerance in wild-type cells only slightly, GSH was important for residual metal resistance in cells without metal efflux systems. In mutant cells without the P-type ATPase ZntA, the additional deletion of the GSH biosynthesis system led to a strong decrease in resistance to Cd(II) and Zn(II). Likewise, in mutant cells without the P-type ATPase CopA, the removal of GSH led to a strong decrease of Cu(II) resistance. The precursor of GSH, γ-glutamylcysteine (γEC), was not able to compensate for a lack of GSH. On the contrary, γEC-containing cells were less copper and cadmium tolerant than cells that contained neither γEC nor GSH. Thus, GSH may play an important role in trace-element metabolism not only in higher organisms but also in bacteria.

Molecular genetic evidence for overlap between general cognitive ability and risk for schizophrenia: A report from the Cognitive Genomics consorTium (COGENT)

Abstract: It has long been recognized that generalized deficits in cognitive ability represent a core component of schizophrenia (SCZ), evident before full illness onset and independent of medication. The possibility of genetic overlap between risk for SCZ and cognitive phenotypes has been suggested by the presence of cognitive deficits in first-degree relatives of patients with SCZ; however, until recently, molecular genetic approaches to test this overlap have been lacking. Within the last few years, large-scale genome-wide association studies (GWAS) of SCZ have demonstrated that a substantial proportion of the heritability of the disorder is explained by a polygenic component consisting of many common single-nucleotide polymorphisms (SNPs) of extremely small effect. Similar results have been reported in GWAS of general cognitive ability. The primary aim of the present study is to provide the first molecular genetic test of the classic endophenotype hypothesis, which states that alleles associated with reduced cognitive ability should also serve to increase risk for SCZ. We tested the endophenotype hypothesis by applying polygenic SNP scores derived from a large-scale cognitive GWAS meta-analysis (~5000 individuals from nine nonclinical cohorts comprising the Cognitive Genomics consorTium (COGENT)) to four SCZ case-control cohorts. As predicted, cases had significantly lower cognitive polygenic scores compared to controls. In parallel, polygenic risk scores for SCZ were associated with lower general cognitive ability. In addition, using our large cognitive meta-analytic data set, we identified nominally significant cognitive associations for several SNPs that have previously been robustly associated with SCZ susceptibility. Results provide molecular confirmation of the genetic overlap between SCZ and general cognitive ability, and may provide additional insight into pathophysiology of the disorder.

Podzol: Soil of the Year 2007. A review on its genesis, occurrence, and functions

Abstract: The Podzol has been elected “Soil of the year 2007” in Germany. This article reviews the present knowledge on the development, functions, and threats of Podzols. The main theories on mobilization and transport of organic matter, Fe, Al, and Si are (1) metal-organic migration, (2) metal reduction, and (3) inorganic sol migration. Immobilization theories include precipitation or polymerization due to increasing pH/abundance of base cations with depth, mechanical filtering in soil pores, oxidation of metal-organic complexes, biodegradation of the organic part, decreasing C-to-metal ratios during translocation, adsorption to soil particles, and flocculation at the point of zero charge. Podzolization is discussed also on the catena scale, where vertical and lateral translocation processes (across pedon boundaries) need to be considered to understand Podzol patterns in landscapes. Chronosequence studies show that incipient podzolization usually becomes visible between 100 and 500 y and mature Podzols develop in 1,000–6,000 y. The occurrence of Podzols worldwide is concentrated mainly on the boreal zone and mountain regions within the humid temperate zone. Smaller Podzol areas are found in some perhumid tropical and subtropical regions. In Germany, Podzols occur in the Alps, in the glaciofluvial valleys and heathlands of N Germany, and in the mountain ranges. They fulfil several ecological functions, especially for groundwater recharge. Main threats for these mostly sandy soils are wind erosion and surface mining of sand. Two pedons which were chosen to represent the “Soil of the year 2007” are presented. Finally, some conclusions about podzolization processes are drawn, which may explain the diverse observations reported in the literature.

Inter- and intra-tumoural heterogeneity in cancer-associated fibroblasts of human pancreatic ductal adenocarcinoma.

Abstract: Cancer-associated fibroblasts (CAF) are orchestrators of the pancreatic ductal adenocarcinoma (PDAC) microenvironment. Stromal heterogeneity may explain differential pathophysiological roles of the stroma (pro- versus anti-tumoural) in PDAC. We hypothesised that multiple CAF functional subtypes exist in PDAC, that contribute to stromal heterogeneity through interactions with cancer cells. Using molecular and functional analysis of patient-derived CAF primary cultures, we demonstrated that human PDAC-derived CAFs display a high level of inter- and intra-tumour heterogeneity. We identified at least four subtypes of CAFs based on transcriptomic analysis, and propose a classification for human PDAC-derived CAFs (pCAFassigner). Multiple CAF subtypes co-existed in individual patient samples. The presence of these CAF subtypes in bulk tumours was confirmed using publicly available gene expression profiles, and immunostainings of CAF subtype markers. Each subtype displayed specific phenotypic features (matrix- and immune-related signatures, vimentin and α-smooth muscle actin expression, proliferation rate), and was associated with an assessable prognostic impact. A prolonged exposure of non-tumoural pancreatic stellate cells to conditioned media from cancer cell lines (cancer education experiment) induced a CAF-like phenotype, including loss of capacity to revert to quiescence and an increase in the expression of genes related to CAF subtypes B and C. This classification demonstrates molecular and functional inter- and intra-tumoural heterogeneity of CAFs in human PDAC. Our subtypes overlap with those identified from single-cell analyses in other cancers, and pave the way for the development of therapies targeting specific CAF subpopulations in PDAC. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.